<!DOCTYPE html>
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<!-- 必须加 -->
<meta http-equiv="X-UA-Compatible" content="IE=Edge，chrome=1">
<!-- 如果引入css文件，则下面两个js必须在引入css之后引入 -->
<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
<script src="https://oss.maxcdn.com/libs/respond.js/1.3.0/respond.min.js"></script>
<style>
@media screen and (max-width: 700px) {
    body {
        background-color:red;
    }
}
</style>

</head>
<body>
	<div id="aa">css @media2</div>
</body>
</html>